Thermal conductivity determination of suspended mono- and bilayer WS₂ by Raman spectroscopy

We report the thermal conductivities of monolayer (1L) and bilayer (2L) WS₂ grown by chemical vapor deposition (CVD), which are determined by use of temperature and excitation dependences of E_2g¹ and A_1g Raman modes. The first-order temperature coefficients of E_2g¹ and A_1g modes in both supported and suspended WS₂ layers were extracted. The frequency shift of the A_1g mode with temperature is larger than that of the E_2g¹ mode for 1L-WS₂, which is attributed to stronger electron-phonon coupling for the A_1g mode than that for the E_2g¹ mode. Moreover, by use of the shift of the phonon mode induced by laser heating, the thermal conductivities at room temperature were estimated to be 32 and 53 W/(m·K) for 1L- and 2L-WS₂, respectively. Our results provide fundamental information about the thermal properties of WS₂ layers, which is crucial for developing applications of atomically-thin WS₂ devices.